"We faced a weapon which we had never, ever faced before in our life, [and] an inability to trace that evidence such we do with either DNA or firearms or fingerprints."

Photo: Joseph Persichini (center), Assistant Director in Charge of the FBI's Washington Field Office, with U.S. Attorney Jeff Taylor (left), District of Columbia, and Chief Postal Inspector Alexander Lazaroff of the U.S. Postal Service, explains recent developments in the government's Amerithrax case.

The story of the U.S. government's investigation into Dr. Bruce E. Ivins and his suicide by drug overdose as federal authorities closed in to arrest him last week has all the suspense of a big-budget Hollywood legal drama. And as is often the case with such dramas, this one may not have a neat ending.

However, the public may find some answers. Due to intense public interest in the case, a federal judge earlier this week took the extraordinary step of unsealing documents pertaining to the Justice Department's investigation of the case. Now analysis of the evidence can begin and perhaps some kind of closure can be found in the episode U.S. Attorney for the District of Columbia, Jeffrey Taylor, called "the worst act of bioterrorism in U.S. history."

The Justice Department has released a catalog of documents that detailed its case against Ivins. Based on this evidence, the department believes Ivins was the sole person responsible for the attacks and that "we could prove his guilt to a jury beyond a reasonable doubt," Taylor said at a press conference yesterday. However, Taylor continued, "Had Dr. Ivins been tried, he would have been presumed innocent until proven guilty."

Based on the indications of the evidence and the suicide of the primary suspect in the case, the Justice Department has begun the process of concluding the seven-year investigation. The investigation, known as "Amerithrax," involved 17 FBI Special Agents and 10 U.S. Postal Inspectors in more than 75 searches and more than 9,100 interviews.

And while the case against Ivins is strong, it is mostly circumstantial. However, there are a few pieces of forensic evidence indicating Ivins was the source of the attacks. That evidence includes the flask, from which the anthrax spores used in the attacks were taken, and for which Ivins was responsible, as well as pre-franked envelopes with printing defects traceable to a post office in Frederick, Md.

First, in early 2005, researchers identified the genetically-unique parent material of the anthrax spores used in the mailings as a single flask of spores, known as 'RMR-1029,' that was created and solely maintained by Dr. Ivins at the United States Army Medical Research Institute for Infectious Diseases in Frederick, Md. "This means that the spores used in the attacks were taken from that specific flask, regrown, purified, dried and loaded into the letters. No one received material from that flask without going through Dr. Ivins." Taylor said. "We thoroughly investigated every other person who could have had access to the flask and we were able to rule out all but Dr. Ivins," he continued.

Furthermore, Taylor said, Ivins was a renowned expert in the production and purification of anthrax spores. He was one of a handful of scientists with the capability to create spores of the concentration and purity used in the attacks. The affidavits allege that, not only did Dr. Ivins create and maintain the spore batch used in the mailings, but he also had access to and experience using a lyophilizer. A lyophilizer is a sophisticated machine that is used to dry pathogens and can be used to dry anthrax. "We know others in Dr. Ivins' lab consulted him when they needed to use this machine," Taylor said.

As for the envelopes used in the attacks, they were all pre-franked and sold only at U.S. post offices during a nine-month period in 2001. An analysis of the envelopes revealed several print defects in the ink on the

pre-printed portions of the envelopes. "Based on the analysis, we were able to conclude that the envelopes used in the mailings were very likely sold at a post office in Frederick, Md., area in 2001," Taylor said. Furthermore, Dr. Ivins maintained a post office box at the post office there from which these pre-franked envelopes with print defects were sold.

Breakthrough in Science, Break in the Investigation"This investigation took our agents and scientists to new territory," Joseph Persichini, assistant director in charge of the FBI's Washington field office, said. "An extraordinary amount of research and testing needed to achieve these groundbreaking accomplishments required months and years of trial and error analysis and review.

For example, at the time of the anthrax attacks, the protocols to determine the DNA fingerprint of individual batches of anthrax had not been developed," Persichini explained. "The FBI sought out the best experts in the scientific community and, over time, four highly sensitive and specific tests were developed that were capable of detecting the unique qualities of the anthrax used in the 2001 attacks."

The initial scientific breakthrough came in early 2005. That was the first time the tests used to trace the origin of the bacteria received validation to the point where they could be used as admissible evidence in court. Then in 2007, as investigators continuing working, they narrowed the focus down to Dr. Ivins.

"The ability to use DNA to track this spore or the anthrax that was used is significant," Perischini said, and "we were prepared to use this analysis [of the specimen RMR-1029] if we went to trial," he continued. "We talk about the timeframe that has taken to develop that DNA. But when you think about the universe of samples and the testing and the procedures and the verification that was done, this is a huge development not just for the FBI but all of us in law enforcement. We faced a weapon which we had never, ever faced before in our life, [and] an inability to trace that evidence such we do with either DNA or firearms or fingerprints. This is, I think, a significant development and kudos to the lab folks that have helped," Persichini said.

When asked about the publication of the scientific research leading to the scientific developments that facilitated the isolation of the flask that contained the anthrax used in the attacks, Persichini said "the FBI lab will do that accordingly."

According to the Washington Post, several researchers who participated in the investigation have shared their insights into the fledging field of microbial forensics, including FBI scientist Bruce Budowle, Timothy Read, a DNA researcher at the Porton Down research center in Britain and Paul Keim, a researcher with the Northern Arizona University at Flagstaff.

As for the ability to move forward from this unnerving event, Persichini said something that may be of some comfort. While an inability to bring Ivins to trial precludes concluding the investigation without uncertainty, which is compounded by the volume of circumstantial evidence in the government's case, he offered this to the ladies and gentlemen of the American public: "Thousands of prosecutors in thousands of courthouses prove cases beyond a reasonable doubt using circumstantial evidence. In fact, the standard jury instruction given by judges across the country is that a jury can consider circumstantial evidence and direct evidence, and they both can be given equal weight depending on the jury's view."